The present invention relates to a method and a system for selecting traffic information services which can be received by at least one mobile receiver and which are relevant for a route previously determined by a navigational device linked to at least one receiver.
Modern navigational devices for motor vehicles are capable today of calculating routes even under consideration of the prevailing traffic conditions. For this purpose, information regarding traffic conditions is to be supplied to the navigational devices; broadcast transmitters having digitally coded traffic messages (TMC messages, TMC=traffic message channel) and other sources and services can be used as message sources. However, for this purpose, it is necessary to tune the receiver that is linked to the navigational device to a service that broadcasts traffic reports relevant for the geographical region traversed by the route.
If such a setting is randomly performed, it can happen that a service is tuned to that does not broadcast any or that only broadcasts infrequent messages that are relevant for the route in question.
From German Published Patent Application No. 44 42 413, a method for tuning a mobile radio receiver and a radio receiver is described, where the particular position determined by a navigational device is used to fetch out a program identification code from a list, so that a transmitter is found that broadcasts information relevant for the ascertained position. It is true that good results can, in fact, be attained when the user of a radio receiver would like to receive traffic messages pertaining to his or her particular position and, for that, requires the correct transmitter. However, using the known method, it is not possible to tune a plurality of broadcast transmitters along the route calculated in the particular case, the tuning of the transmitter and the route search being carried out dynamically.
Broadcasting traffic information services is also possible via broadcast media other than RDS broadcasting, e.g. via digital audio broadcasting (DAB) or via cellular networks according to the GSM standard.
It is an object of the present invention to use a navigational device to choose from the available broadcast media and/or transmitters when searching for a route, thereby enabling an optimum supply of traffic information over the entire route.
According to the present invention, this object is achieved in that service information is read out for the determined route from a stored list, the information identifying the services having traffic messages relevant for the route; in that, in the case of a plurality of services, a table is created that contains the read-out service information sorted according to a valuation, and that can be changed as the route is followed; and in that a receiver is set in each case to the highest-rated service.
The valuation can be carried out according to features that characterize the services and can be received together with the services themselves or can be retrieved from a memory at the receiver.
Using the method according to the present invention, the DAB tuner can preferably be set, for example, in regions serviced by DAB, in the remaining regions, the RDS tuner can be set, and on selected routes or in response to a particular demand from the user, commercial services broadcast via GSM can be set. In addition, in each case for one region, it is also possible to store and use traffic reports received from a plurality of services.
One further refinement of the present invention makes it possible when searching for a route with the aid of a navigational device, to select the service that can be received by a receiver in such a manner that the reception of relevant traffic messages is optimized over as much of the entire route as possible.
In present-day radio broadcasting, this is achieved, for example, in that at least one receiver is a radio receiver for receiving transmitters having traffic messages; in that program identification codes are fetched out from a stored list for the determined route, the list identifying transmitters having traffic information relevant for the determined route; in that, in the case of a plurality of fetched-out program identification codes, a table is created that includes the fetched-out program identification codes sorted according to a valuation, and that can be changed as the route is followed; and in that the radio receiver is set in each case to the highest-rated, receivable transmitter.
In the case of additional services, e.g. DAB, this method can be applied once minimal adaptation to the technical specifications of the particular service has been made.
Provided that they are supplied with a sufficient number of traffic messages, navigational devices, which can calculate the route even under consideration of the instantaneous traffic conditions, correct the route on the basis of the traffic messages, both at the start of a trip, as well as during the trip in the case of an initially calculated route. Furthermore, during a trip, it may be necessary to recalculate the route when the vehicle deviates (be it intentionally or not intentionally) from the calculated route. Regardless of this, the method according to the present invention enables the best transmitter available for this purpose to be set.
In the method according to the present invention, it is preferably provided that the stored list for the program identification codes includes information regarding the reception area, the region covered by the message content (message area), the known frequencies, and an additional message selection carried out by the transmitter.
Often, a plurality of transmitters are relevant for one and the same geographical region. In order to also optimize in this context, it is provided in an additional further refinement that the table of the transmitters to be set is established and actualized by comparing positions on the route to regional information in the list. Preferably, the entries in the thus-determined table are sorted in such a manner that transmitters having the most suitable message content are at the top.
In detail in this context, it can also be provided that the sorted table is transferred to a control device of the radio receiver and is used there as a basis for a transmitter search, the transmitter at the head of the table being searched first.
Transmitters often have different preferences for selecting the traffic messages broadcast by them. Thus, there are transmitters, for example, that only broadcast local traffic reports, or ones that broadcast traffic messages for a larger area. In another further refinement, these characteristics of the transmitter can be taken advantage of in that, in the sorting operation, the particular class of the roads to be traveled are in relation to the other message selection of the transmitter that identifies the road classes for which the transmitter in question broadcasts traffic messages.
According to an advantageous embodiment, the different transmitters or PI codes can be geographically selected in a particularly advantageous manner without the relatively complicated storing of coordinates, in that corresponding program identification codes are specified in the list regarding geographical regions into which a digital road map is subdivided for the navigational device, and in that the program identification codes are read out on a region-by-region basis and sorted as the route is followed.
In this advantageous embodiment, it is possible to take the road classes into exact consideration in that, in the sorting operation, the particular class of the roads to be traveled is in relation to the other message selection of the transmitter that designates the size of the region for which the transmitter in question broadcasts traffic messages, and in that, in the case of different road classes within one region, those which are most prevalent within one region are used for the sorting.
In an advantageous system for implementing the method according the present invention, it is ensured that the current state of the list and the digital road map reliably agree by the list being stored on the same data carrier as a digital road map, preferably on an optically readable disc (CD ROM).
To continuously adapt the route to potentially quickly changing traffic conditions, frequent access to TMC transmitters may be necessary. So that this is not associated with disturbing interruptions in the reception of the remaining programs, it is provided in another advantageous system for implementing the method according to the present invention that the radio receiver has two receiving sections, which can be set independently of one another.